In recent years, flat panel displays are used in various commodity products and fields, and thus flat panel displays are required to have a large size, high image quality and low power consumption.
Under the circumstances, organic EL display devices, which include an organic EL (electroluminescent) element that utilizes electro luminescence of an organic material, are attracting great attention as all-solid state flat panel displays that are excellent as having capability of low voltage operation, quick responsivity and light emission.
The above organic EL element is provided with an anode, a cathode, and a luminescent layer formed between the anode and the cathode. In such an organic EL element, in order to enhance luminescence efficiency in the luminescent layer, a hole injection layer or a hole transport layer is provided between the anode and the luminescent layer, or an electron injection layer or an electron transport layer is provided between the cathode and the luminescent layer.
Further, it has been proposed that the above organic EL element is configured to emit light having a plurality of peaks.
Specifically, in a conventional organic EL element, as described in Patent Document 1 below for example, a plurality of luminescent layers are provided to emit light having a plurality of peaks. Further, in the conventional organic EL element, an electron supply layer made of a high electron mobility compound is provided between the cathode and the luminescent layer to adjust the carrier balance between holes and electrons in the respective luminescent layers.